Figure 3Terms contributing to the energy resolution and total energy resolution in each of the four gratings. (a) Resolution due to a 30 µm exit slit and meridional RMS slope errors of 0.2 µrad on M2 and LEG grating. (b) Resolution due to a 20 µm exit slit and meridional RMS slope errors of 0.2 µrad on M2 and MEG grating. (c) Resolution due to a 10 µm exit slit and meridional RMS slope errors of 0.2 µrad on M2 and HEG grating. (d) Resolution due to a 5 µm exit slit and meridional RMS slope errors of 0.2 µrad on M2 and 0.1 µrad on VEG grating. (e) The total resolving power of four gratings with slit sizes listed in (a)–(d). (f) Spot pattern at the exit plane for 1000 eV and 1000.011 eV with VEG.